Forest fires present a serious hazard to humans and ecosystems in many parts of the world, and fires over large forest ecosystems can be a major agent of conversion of biomass and soil organic matter to CO2.

Here we make use of the McArthur Forest Fire Danger Index, which is calculated from daily maximum temperature, daily minimum relative humidity, daily mean wind speed, and a drought factor which is based upon daily precipitation. We do not take account of other factors such as changing extent or characteristics of vegetation cover or population changes.

We identify that the primary meteorological driver of projected changes in forest fire danger on the global scale is temperature, followed by relative humidity which itself is strongly influenced by temperature. In terms of global and regional climate projections, we have more confidence in the direction and magnitude of these projected changes compared to changes in precipitation and wind speed, which make less of a contribution to the results.

Fire danger is projected to increase over most parts of the world compared to present-day values. The largest proportional increases are seen under the A1B SRES and IMAGE (Integrated Model for Assessment of Greenhouse Effect) scenarios for Europe, Amazonia and parts of North America and East Asia. These scenarios were described by the IPCC (Intergovernmental Panel on Climate Change) to help make projections of future climate change. Increases in fire danger are lower under the mitigation scenario (E1), but generally affecting the same regions as under both of the A1B scenarios considered here.